Process for the preparation of easily watersoluble acid sulphuric acid ester derivatives of indanthrone dyestuffs



Patented Apr. 30, 1935 UNITED STATES PATENT OFFICE PROCESS FOR THE PREPARATION .OF

EASILY WATERSOLUBLE ACID SULPHURIC ACID ESTER DERIVATIVES OF INDAN- THRONE DYESTUFFS Roger Ratti, Basel, Switzerland,

asslg'nor to Durand & Huguenin S. A., Basel, Switzerland Claims.

The U. s. Patent No. 1,448,251 discloses a process for the manufacture of water soluble esterlike derivatives of vat dyestufis, especially valuable for dyeing and printing purposes, consisting in treat ing the leuco compounds of vat dyestuffs with chlorosulphonic acid in presence of a tertiary base, and transforming the thus formed ester into a stable alkali salt. This process has been modified and improved since.

It is known, that the vat dyestuff N-dihydro- 1,2,2'1' dianthraquinone azine (indanthrone) when transformed into its leuco compound and the latter esterified according to the process described in the aforesaid patent, yields a stable and to a certain extent water soluble product. But as the product is intended to be applied for printing textile fibres, its water solubility is insufficient. The analysis shows, that the product in question is a disulphuric acid ester of leuco N -dihydro- 1,2,2 1 -dianthraquinone-azine.

Surprisingly it has now been found, that a new estersalt, also derived from the vat-dyestufi N- dihydro-1,2,2',l-dianthraquinone-azine, but of much better solubility than the one manufactured according to the said Patent No. 1,448,251 can be obtained by a new method of working. The manufacture of this new estersalt does not start from N-dihydro-l,2,2',1-dianthraquincne-azine (ordinary indanthrone) but from 1,2,2,1-dianthraquinone-azine obtained from the former by oxidation.

By simultaneous reduction and esterification of this 1,2,2,1'-dianthraquinone-azine in known manner with the aid of an addition product of a tertiary base and $03, in presence of an excess of the tertiary base, in presence of a metal and when carrying out the esterification in the absence of any moisture, so that during the operation no acid can be formed, a substance is obtained which can be converted into a stable easily soluble alkali-salt. It appears that in this process the four keto-groups of the anthraquinones are simultaneously reduced to enolic-groups and esterifled, so that the tetrasulphuric acid ester of tetrahydro-l,2,2,i' dianthraquinone azine is formed.

In a similar way a valuable poly-ester (probably a mixture of a triand tetra-sulphuric acid ester) is obtained, when treating a chloro-derivative of the 1,2,2,l-dianthraquinone-azine in the above said manner.

The above mentioned poly-esters are exceedingly sensitive against acids. If an acid is added to a solution of such an ester, a violet or blueviolet almost insoluble body is precipitated. It is identical or very similar to the well known diester. It is an unexpected fact that by acid oxidation hydrolysis and oxidation) not the parent material, that is 1,-2,2,1'-dianthraquinone-azine, but N-dihydro-l,2,2',1-dianthraquinone azine (indanthrone) is formed. Therefore, these ester salts can-be used for dyeing and as they show a very good water solubility, they are particularly suitable for printing textile fibres.

The same or similar bodies appear to have already been obtained, but in quite a difierent manner, namely by means of oxidation of the 2- aminoanthrahydroquinone-disulphuric acid ester or its chloro-derivatives in alkaline solution (see German Patent 'No. 470,809 and British Patent No. 334,902).

The new process is illustrated by the following examples:

Example 1 20 grs. of pure S03 are added'drop by drop, while cooling withice and stirring, to 250 grs. of water free pyridine. To this addition-product is added in the cold, while stirring, a mixture of 22 grs. of 1,2,2',1-dianthraquinone-azine and 22 grs. of copper powder. The mass is heated up to 70 C. in a dry current of nitrogen, free from air, and kept at this temperature for about 1 hours. The color of the mass, which at first is green, turns slowly to blue, afterwards to violet and finally to deep-red. The mass is allowed to cool down and then poured into a mixture of 70 grs. of caustic soda lye (30%) and ice. Then the solution is heated up for a short time to 50 C., separated from copper by filtration and the pyridine distilled off under a vacuum. The thus obtained alkaline solution is of a yellowish brown color and shows a strong, green fluorescence. By evaporation in vacuo the solution is concentrated to a paste.

Example 2 25 grs. of pure S03 are added drop by drop, while cooling with ice and stirring, to 250 grs. of water free pyridine. To this addition-product is added in the cold, while stirring, a mixture of 25 grs. of dichloro-1,2,2',1'-dianthraquinone-azine (obtained according to the German Patent No. 229,166) and 25 grs. of copper powder. The mass is heated up to 70 C. in a dry current of nitrogen, free from air and kept at this temperature for about 1 hours. It is then allowed to cool down and poured into a solution of 35 grs. of potassium hydroxide in 3 off by filtration. The filtrate is of a brown color and shows a green fluorescence. By evaporation in vacuo an easily soluble product, probably a tetraester is obtained. r

The product, suitable for printing purposes, being a mixture of the sodium salt of ,theftwo esters will be obtained, when pouringthe red colored mass into a mixture of '70 grs of caustic soda lye (30%) and 3 litres of ice-water instead of pouring it into a solution of potassium hydroxide, as indicated above. The mass-is left standing for a iew hours-and heated'up-afterwards, while stirring, to EEO-60 C." After separation from copper by filtration, the solution is concentrated by evaporation in vacuo to a paste; By the same working operation a mixture of poly-esters results, when for example a trichloro derivative of the 1,2,2,1'-dianthraquinone-azine is used as starting material.

[he process of esterification as illustrated by the above examples is not'limited to the use of pyridine and copper. Another tertiary base and another metal, known to be suitable in vat-dyestuii esterification and for reducing purposes, respectively, may be used.

What I claim is:- l. A process for the preparation of easily 7, watersoluble acid sulphuric acid esters of the leuco compound of a 1,2,2',1-dianthraquinoneazine, with the aid of an addition product of a tertiary base, suitable for esterification, and S03, in presence of an excess of the tertiary base and a metal as used for, reduction, said process yielding easily soluble triand tetra-esters and consisting in using an 1,2,2,1'-dianthraquinoneazine as starting material and carrying out the esteri'fication in the absence of any moisture, so that no acid can be formed during the operation.

2. A process for the preparation of easily \vatersoluble acid sulphuric acid esters of the leuco compound of a 1,2,2,1'-dianthraquinone azine, with the aid of an addition product of a tertiary base, suitable for esterification, and S03, in presence of an excess of the tertiary base and a metal as used for reduction, said process yielding easily soluble triand tetra-esters and consisting in using a halogenated l,2,2',l-dianthrai quinone-azine as starting material and carrying out the esterification in the absence of any moisture, so that no acid can be formed during the operation.

, 3.'A process for the preparation of easily watersoluble acid sulphuric acid esters of the leuco compound of a 1,2,2,1'-dianthraquinone- "azine, with the aid of an addition product of a tertiary base, suitable for esterification, and S03,

in presence of an excess of the tertiary base and a metal as used for reduction, said process yield- .ing easily soluble triand tetra-esters and consisting in using chlorinated l,2,2,1dianthraqu'inone-azine as starting material and carrying out the esterification in the absence of any moisture, so that no acid can be formed during the operation.

4. A process for the preparation of easily watersoluble acid sulphuric acid esters of the leuco compound of a 1,2,2,l'-dianthraquinoneazine, with the aid of an addition product of a tertiary base, suitable for esterification, and S03, in presence of an excess of the tertiary base and a metal as used for reduction, said process yielding easily soluble triand tetra-esters and consisting in using a dichloro-l,2,2,l-dianthraquinone-azine, as starting material and carrying out the esterification in the absence of any moisture, so that no acid can be formed during the operation. 7

5. A process for the preparation of easily watersoluble acid sulphuric acid esters of the leuco compound of a 1,2,2',l-dianthraquinone azine, with the aid of an addition product of a tertiary base, suitable for esterification,

and $03, in presence of an excess of the tertiary base and a metal as used for reduction, said process yielding easily soluble triand tetraesters and consisting in using l,2,2',l'-dianthraquinone-azine as starting material and carrying out the esterification in the absence of any moisture, so that no acid can be formed during the operation.

ROGER RATTI. 

